electromagnetic spectrum

Radio waves

Terrestrial radio/TV as they can travel long distances , MRI to generate images of the human body

Microwaves

Microwave oven as water molecules in the food absorb radiation and gain thermal energy cooking it. Mobile phones when waves are sent out by the transmitter. GPS as waves pass through the atmosphere the satellites to find the receiver’s location. Can cause internal heating of body cells and damage them

Infrared

Remote controls, cookers as it give out thermal radiation. Thermal imaging camera. Can cause skin burns

Visible light

Illuminations, vision and photography. Can burn at higher intensity eg with lasers

Ultraviolet

Security marks on bank notes, sterilise water by killing bacteria. Can cause skin cancer, cataracts and burns to surface cells

Fluorescent

It absorbs UV light and emits visible light

X rays

X ray images, crack detection, CAT scans. Can cause ionisation in skin and eyes, damaging and causing mutations in the DNA

Gamma rays

Sterilisation, radiotherapy to treat cancer. Can cause ionisation of cells and damage the DNA

Similarities between electromagnetic waves

• all transverse waves

• All travel at the speed of light

• Can travel through a vacuum

• Can transfer energy

How does microwaves heat food up?

Microwaves are absorbed by water molecules in the food which heats up when internal energy increases